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Abstract:

An electric damper for damping the relative movement between a first and
a second mass includes a generator integrated into a gear and driven by
the movement of the first and second masses. A first gear element forming
a stator is set into rotation by the movement of the masses. A second
gear element forming a rotor is rotated by the rotation of the first gear
element. The second gear element is directly or indirectly coupled to the
first gear element with a gear ratio. Either the first or the second gear
element includes means for generating a magnetic field.

Claims:

1.-8. (canceled)

9. An electric damper for damping relative movement between a first and a
second mass, comprising: a generator driven by the movement between the
first and the second mass, said generator being integrated into a gear
comprising a first gear element forming a stator and being set into
rotation by the movement between the first and the second mass, and a
second gear element forming a rotor and rotated by rotation of the first
gear element, said second gear element coupled directly or indirectly to
the first gear element with a gear ratio, and means for generating a
magnetic field disposed on the first gear element or the second gear
element.

10. The damper of claim 9, wherein the means for generating a magnetic
field comprise a plurality of windings disposed on the first gear element
for external excitation or several permanent-magnetic elements for
self-excitation, and wherein the second gear element comprises a
plurality of windings for guiding a generated current.

11. The damper of claim 9, wherein the means for generating a magnetic
field comprise a plurality of windings disposed on the second gear
element for external excitation or several permanent-magnetic elements
for self-excitation, and wherein the first gear element comprises a
plurality of windings for guiding a generated current.

12. The damper of claim 9, wherein the second gear element is ring-shaped
or cylindrical, and the first gear element arranged interiorly of the
first gear element.

13. The damper of claim 9, wherein the first gear element is ring-shaped
or cylindrical, and the second gear element arranged interiorly of the
first gear element.

14. The damper of claim 9, wherein a rotation direction of the first gear
element opposes a rotation direction of the second gear element.

15. The damper of claim 9, wherein the gear is a harmonic drive gear
comprising: a ring-shaped or cylindrical flexible unit forming the first
gear element and having external teeth, a rigid unit with internal teeth
meshing with the external teeth of the flexible unit, and an oval rotary
element arranged interiorly of the flexible unit and cooperating with the
flexible unit and deforming the flexible unit.

16. The damper of claim 15, further comprising a flexible rolling bearing
arranged between the first gear element and the second gear element.

17. The damper of claim 16, wherein the flexible rolling bearing is
constructed as a roller bearing or as a needle bearing.

18. The damper of claim 9, wherein the gear is a planetary gear
comprising: a ring gear forming the first gear element, planet gears
meshing with the ring gear, and a sun gear meshing with the planetary
gears and forming the second gear element.

19. The damper of claim 9, wherein the gear is a cycloidal gear
comprising: a ring-shaped or cylindrical unit forming the first gear
element, a stationary housing part having a first toothed profile, and a
cam disk connected to the first gear element and having an edge with a
second toothed profile meshing with the first toothed profile, wherein
the second gear element engaging with the first gear element is arranged
on the cam disk.

20. The damper of claim 19, wherein the second gear element is disposed
in a borehole of the cam disk.

Description:

[0001] The invention relates to an electric damper for damping relative
movement between a first and a second mass and includes a generator
driven by the movement of the masses.

[0002] In many technical fields, relative movements between two components
of an oscillating mechanical system need to be damped. One example, which
however is not limiting, relates to vibration damping in an automobile
body in the region where the automobile body is suspended on the
undercarriage. Predominantly, hydraulic dampers are used. However,
hydraulic dampers are not capable of recovering or reusing the energy
extracted from the system during damping.

[0003] DE 101 15 858 A1 discloses an electric damper with a generator
driven by the movement of the masses. A generator typically includes a
stator and a rotor which can rotate relative to the stator and magnetic
field generating means, wherein a current is generated during the
rotation of the rotor relative to the stator because the rotation takes
place in the magnetic field, i.e. energy is recovered. Accordingly,
damping is produced, on one hand, by the energy required for performing
the rotation in the magnetic field and, on the other hand, the energy is
utilized in form of a current produced by the generator, which can be
supplied to the onboard network.

[0004] In the system disclosed in DE 101 15 858 A1, the generator is
mounted on the vehicle body, i.e. the stator is fixedly attached to the
vehicle body on a first damper part. The rotor is connected with the
second damper part which can move linearly relative to the first damper
part by way of a gear, for example a threaded ball spindle. The threaded
spindle is received in a threaded nut fixedly connected in the second
damper part. When the second damper part executes a linear motion, the
threaded spindle is rotated, causing a rotary motion of the rotor.
Although the ratio between the rotary motion and the linear motion of the
damper can be increased to a certain extent, the described system has a
very complex structure and the conversion of the linear motion into the
rotary motion performed by the gear is error-prone.

[0005] The invention therefore addresses the problem of providing an
electric damper with a simpler structure that operates reliably.

[0006] For solving this problem, an electric damper of the aforedescribed
type is provided, wherein the generator is integrated in the gear,
wherein a first gear element forming a stator is set into rotation by the
movement of the masses, via which a second gear element which forms a
rotor and is directly or indirectly coupled with a gear ratio by way of
the first gear element is rotated, wherein means for generating a
magnetic field are provided on the first or on the second gear element.

[0007] With the electric damper according to the invention, the generator
is particularly advantageously integrated directly into the gear, and is
not connected after the gear as in the state-of-the-art. This allows the
configuration of a very small unit. In addition, the functional principle
of the damper according to the invention as compared to the conventional
damper is entirely novel. The stator itself is not a stationary component
and is instead actively rotated during operation. I.e., the stator is in
some way directly or indirectly coupled with one of the moving masses,
such that the stator is set in rotation during a movement of the masses.
Due to the direct or indirect coupling of the stator provided by the gear
ratio, this rotation inherently causes the rotation of the second gear
element forming the rotor, which rotates in the magnetic field when
magnetic field generating means are provided on the stator, thus causing
rotor-side current generation in current generating means provided for
this purpose. I.e., only rotary motions are used or introduced into the
damping system which enable damping via the generator or the generator
function as well as recovery of the damping energy in form of the current
generated on the generator side. When using such gear, a relatively large
relative movement between the stator and the rotor, which depends only on
the gear ratio, can be obtained, which can be increased further by
designing the gear such that the rotation direction of the first gear
element is opposite to the rotation direction of the second gear element.
In other words, both gear elements rotate in opposite directions, thereby
increasing the relative travel between the two gear elements during this
rotary motion compared to a rotation in the same direction. With the
opposing movement of the stator, the relative speed between the
magnetic-field-generating elements, or the current-generating elements of
the stator and the rotor is inherently also increased. Overall, a
smoothing effect of the damping is attained with the opposing rotary
motions, while simultaneously increasing the efficiency. The field
generating means can be provided either on the stator so that the current
is generated on the rotor side. Alternatively, the field generating means
may also be provided in the rotor, so that current on the stator is
generated in current generating means provided on the stator.

[0008] On the stator itself, i.e. on the first gear element, either
several windings may be provided as field generating means, which allow
external excitation, meaning that current must flow through these
findings to produce the magnetic field. Alternatively, several
permanent-magnetic elements may be provided on the stator for
self-excitation. On the rotor itself, i.e. on the second gear element,
several windings for guiding the generated current are provided as
current generating means, i.e. current is induced at that location. The
current can be tapped at these windings and supplied, for example, to the
onboard network of an automobile having an installed damper. It will be
understood that the current-generating parts can also be arranged in a
reverse manner, meaning said the windings generating the magnetic field
or the permanent magnets may be provided on the rotor and the induction
windings on the stator.

[0009] Different types of gears may be used as gears. According to a first
embodiment of the invention, the gear may be a harmonic drive gear. Such
harmonic drive gear includes a ring-shaped or cylindrical flexible unit
forming the first gear element and having external teeth, a rigid unit
having internal teeth meshing with the external teeth of the flexible
unit, and an oval rotary element forming the second gear element, which
is arranged in the interior of the flexible unit and cooperates with the
flexible unit while deforming the flexible unit. The field-generating
windings or the field-generating permanent-magnetic elements, which form
flex splines, are arranged on the flexible unit, typically referred to as
flex spline, forming the stator. The rigid unit, typically also referred
to as circular spline, represents a housing component of the gear and is
fixedly arranged in relation to the stator and the rotor. The external
teeth of the flex spline engage with the internal teeth of the circular
spline, whereby the number of teeth is different, as is typical with
harmonic drive gears. Lastly, an oval rotary element forming the rotor is
provided, which cooperates with the flexible unit, deforms the flexible
unit and thus changes the tooth engagement and/or the angular position of
the tooth engagement between the external teeth of the flex spline and
the internal teeth of the circular spline in a conventional manner.

[0010] When the stator is fixedly connected with a pivotally supported
component, for example a transverse control arm and the like, the flex
spine is twisted relative to the circular spine, resulting in a rotation
of the oval rotary element, i.e. the rotor, due to a change in the
deformation of the flex spine. The rotation angle of the flex spline,
i.e. of the stator, is, for example, 1/4 to 1/2 of a revolution, whereas
the rotor rotates several times by 360° due to the gear ratio. The
operation of the gear is therefore just the opposite of typical
applications of a harmonic drive gear, wherein the rotary element is
actively rotated and the flex spline operates quasi as an output.

[0011] To allow the oval rotary element to roll on the stator, i.e. the
flex spline, as easily as possible, a flexible rolling bearing is
advantageously arranged between the first and the second gear element, in
particular a roll bearing and a needle bearing, which significantly
reduces friction between the two gear elements.

[0012] An alternative type of a gear is a planetary gear. This planetary
gear includes a ring gear forming the first gear element, planetary gears
which are fixedly arranged on a corresponding housing component of the
gear and mesh with the ring gear, and a sun gear meshing with the
planetary gears and forming the second gear element. The ring gear then
forms the stator which is slightly rotated by the mass to which it is
coupled, for example, via a transverse control arm and the like. Because
of the coupling via the planetary gears, the sun gear forming the rotor
is then rotated by the stator rotation with a gear ratio, wherein the
rotor is of course located inside the cylindrical or ring-shaped ring
gear, thereby producing damping in connection with current generation.

[0013] A third type of gear configured to utilize the damper according to
the invention is a cycloidal gear. This type of gear includes a
ring-shaped or cylindrical unit which forms the first gear element and is
connected with a cam disk having an edge with a tooth-shaped profile,
which in turn meshes with a stationary housing part having a tooth-shaped
profile, wherein a second gear element is arranged on the cam disk,
preferably in a borehole, and engages with the first gear element. Such
cycloidal gear also allows a high gear ratio, so that the small angular
rotation of the first gear element, i.e. the stator, is transmitted to
the rotor, i.e. the second gear element, with a high gear ratio. The
second gear element is here eccentrically arranged on a cam disk having
an outer undulated profile, with the cam disk rotating inside a
stationary housing ring having a corresponding opposing toothed pattern,
while being radially movable in the housing ring. In addition, the first
gear element, i.e. the ring-shaped or cylindrical unit, which has
corresponding coupling pins and engages in large-diameter boreholes of
the cam disk, is coupled with the cam disk so that the cam disk can
perform the radial movement while the first gear element, i.e. the
stator, is rotation-locked on the rotation axis. The operation of such
cycloidal gear is sufficiently known, and the integration of the
generator here also results in excellent, smooth damping.

[0014] Other advantages, features and details of the invention are
described in the following exemplary embodiments and illustrated the
appended drawings, which show in:

[0015] FIG. 1 an explosive view of a damper according to the invention in
a first embodiment,

[0016] FIG. 2 the damper of FIG. 1 in an assembled view,

[0017] FIG. 3 a front view of the damper of FIG. 2,

[0018] FIG. 4 a damper installed in a rocker arm,

[0019] FIG. 5 a schematic diagram of a possible installation situation of
a damper in the region of an automobile axle,

[0020] FIG. 6 an explosive view of a damper according to the invention in
a second embodiment,

[0021] FIG. 7 a schematic diagram of the assembled damper of FIG. 6,

[0022] FIG. 8 an explosive view of a damper according to the invention in
a third embodiment, and

[0023] FIG. 9 a perspective view of the assembled damper of FIG. 8.

[0024] FIG. 1 shows an explosive view of an electric damper 1 in a first
embodiment according to the invention. The damper includes a gear in
which a generator is directly integrated. The damper includes a first
gear element 2 forming a stator and having means for generating a
magnetic field. This first gear element 2 is formed in the illustrated
gear, a harmonic drive gear, of a flexible cylindrical bushing, the
so-called flex spline, which has a toothed pattern 3 on its outside.
Unillustrated permanent magnets for possible self-excitation or windings
for a possible external excitation for generating the magnetic field are
provided on the inside.

[0025] A second gear element 4 forms the rotor, wherein this second gear
element 4 is set in rotation by a rotation of the flex spline itself. To
this end, the second gear element 4 includes an oval disk-shaped rotary
element 5, on which an elongated body 6 is arranged which in turn has
several segments 7 with windings 8, with current being induced in the
windings 8 during a rotation. A flexible rolling bearing 9 with several
roller-shaped and needle-shaped rolling bodies 10 and a flexible
ring-shaped bearing cover 11 are arranged on the oval rotary element 5.
In the assembled position, the second gear element 4 is inserted into the
first gear element 2 such that the rolling bearing 9 and the flexible
cover 11, respectively, contact the inside of the segment of the first
gear element having the external teeth 3. The first gear element 2, i.e.
the flex spline, is distorted into an oval shape by the oval rotary
element 5 in conjunction with the rolling bearing 9. The oval rotary
element 5 then has the function of a typically provided wave generator.

[0026] Also provided is a rigid unit 12 which is to be rigidly coupled
with a third element. The rigid unit 12 has a central opening with
internal teeth 13 meshing with the external teeth 3 of the first gear
element 2, i.e. the flex spline. This rigid unit 12 forms the circular
spline, which is known from a harmonic drive gear. Because the internal
toothed pattern 3 has a smaller number of internal teeth 3 and a somewhat
smaller diameter than the external toothed pattern 13, the flex splines
rotate in a conventional manner like in conventional harmonic drive gears
when the flex generator, in this case the rotary element 5, rotates.
However, the damper according to the invention operates in the opposite
manner, with the first gear element 2, i.e. the flex splines, rotating
and thereby resulting in a significantly larger rotation of the second
gear element 4, in this case the rotor, as a result of the gear ratio.

[0027] FIGS. 2 and 3 show the damper 1 in an installed position. As can be
seen, the second gear element 4, i.e. the rotor, is located inside the
first gear element 2, in this case the stator, showing on its inside an
exemplary winding 14 for producing a magnetic field. The external teeth 3
of the first gear element 2 engage with the internal teeth 13 of the
stationary rigid unit 12. This can be clearly seen from the diagram of
FIG. 3 which shows a front view of the electric damper 1 of FIG. 1. This
front view illustrates the flexible unit 2 is in addition to the rigid
unit 12, when looking at the front face. However, the opposite end of the
flexible first gear element having the toothed pattern is distorted into
the shape of an oval by the oval rotary element 5, so that it is here
also deformed into an oval with a horizontal orientation in the tooth
engagement region, with the external teeth 3 being able to engage with
the internal teeth 13 in this region, whereas the toothed pattern 3 is
not an engagement with a toothed pattern 13 in the region of the vertical
deformation axis. The deformation is caused by the oval rotary element 5
which, as described above, presses with the needle-shaped or
roller-shaped rolling bearing 10 and the support 11 shaped as an exterior
ring against the inside wall of the segment having the external teeth 3.

[0028] In the installed position, as shown in the example of FIG. 4, the
damper 1 is inserted with the first gear element into a borehole 15 of a
lever element 16, see FIG. 4. The first gear element 2, i.e. the stator
and/or the flex spline, is fixedly connected with the lever element 16,
so that the gear element is actively rotated by the lever 16 during a
rotation about the borehole axis. This lever rotation and the resulting
rotation of the first gear element 2 forces a rotation of the oval rotary
element 5 via the toothed coupling and thereby of the entire second
rotary element 4, causing the windings 8 to rotate in the generated
magnetic field of the first gear element 2, i.e. the stator, thus
inducing a current. Due to the integration into the gear and the defined
gear ratio, the angle traversed by the second gear element 4 is
significantly greater than the active rotation of the first gear element
2; otherwise, the two rotary motions oppose each other, as indicated in
FIGS. 2 and 3 by the arrows. This necessarily results in a significant
relative rotation of both elements with respect to one another, wherein
the rotor rotation is a multiple of the stator rotation. For example, a
rotation of the first gear element 2, i.e. the flex splines, by
90° can be transformed into a geared rotor movement in the range
of 3-5 complete revolutions. Pure rotations are thus used for damping and
current generation. The damping effect is due to the rotation of the
rotor, i.e. the second rotary gear element 4, in the magnetic field of
the first gear element 2, whereby the energy removed from the system is
not lost, but is recovered to a substantial part through induction of the
current.

[0029] FIG. 5A shows a possible installation situation. Illustrated are as
part of an automobile a wheel 17 and a wheel carrier 18 on which a push
rod 19 is arranged which is connected, for example, with the lever
element 16. The lever element 16 is pivotally supported about the
rotation axis D, wherein the damper 1 according to the invention is
disposed in this rotation axis D. However, the damper 1 may also be
integrated directly in the rotary suspensions of one or both transverse
control arms 20, as illustrated in the exemplary diagram. The stator,
i.e. the first gear element 2, is always connected with the drive and
represents the driven element, wherein the rotor, i.e. the second gear
element 4, is always the driven element. When the wheel 17 is deflected
and rebounds, the lever element 16 is moved by the push rod 19, causing a
rotation about the rotation axis D, thereby operating the damper 1
according to the invention in the aforedescribed manner.

[0030] FIGS. 6 and 7 show a second embodiment of a damper 1 according to
the invention, wherein identical reference symbols are used for identical
or substantially identical components. Because the gear is here
constructed as a planetary gear, a first gear element 2 in form of a ring
gear 21 is here also provided. Again, means for generating a magnetic
field, for example windings 22, are provided on the inside of the ring
gear 21, as well as unillustrated internal teeth 23. In the illustrated
example, three planetary gears 25 which mesh with the internal teeth 23
of the ring gear 21 by way of unillustrated external teeth 26 are
supported for rotation on a rigid, fixed-position support 24.

[0031] In addition, a sun gear 27 is provided, which is part of the second
gear element 4 and meshes via (also unillustrated) external teeth 28 with
the planetary gears 25. The sun gear 27 has an extension with
corresponding sections 39 with windings 29, in which current is induced
during rotation in the magnetic field.

[0032] In the installed state, the rotor, i.e. the two-part gear element
4, is disposed in the cylindrical stator, in this case the first gear
element 2. When, as shown for example in FIG. 1 with respect to a first
embodiment, the damper 1 is inserted in a cylindrical borehole of a
pivoting lever 16 and the first gear element 2 is rigidly connected with
the pivot lever 16, then a rotation of the lever about the rotation axis
of the gear causes the first gear element 2, i.e. the stator, to also
rotate. Due to the gear ratio via the different meshing wheels, the sun
gear 27 rotates, and hence the entire second gear element rotates. The
windings 29 rotate in the magnetic field produced by the windings 22 of
the stator, again causing current generation. The rotation directions of
the rotary element, namely of the first and the second gear element 2, 4,
again oppose one another. With this exemplary embodiment of the
invention, too, excellent damping can be attained in conjunction with a
recovery of the energy removed from the system via the generated current.

[0033] FIGS. 8 and 9 show a third alternative embodiment of an electric
damper 1 according to the invention with an eccentric gear. Here, too, a
first gear element 2 forming the stator is provided. It is formed by a
cylindrical sleeve, with windings 3 for producing a magnetic field
arranged on the inside of the sleeve. Pins 31 are arranged on one end
face, which engage in larger-diameter boreholes 32 of a cam disk 33 which
has an edge with an undulated profile, see FIG. 8. Protruding pins 35 are
provided on a rigid stationary unit 34 which mesh like a toothed
engagement with the profile on the cam disk 33. A pin 35 of the second
gear element 4 is received in a central borehole of the cam disk 33 with
a rotation lock, wherein a body is in turn arranged on this pin 35, with
windings 37 for generating a current arranged on respective shoulders 36
disposed on the pin 35.

[0034] When the first gear element 2, which is in turn rigidly connected
with a pivoting lever 16 or the like, rotates, the cam disk 33 which
meshes at the edge with the pins 35, i.e. the toothed pattern of the
rigid unit 34, is actively rotated. This causes a rotation of the second
gear element 4, as is known for eccentric gears or cycloidal gears of
this type, wherein the rotation of the second gear element 4 is
significantly greater than the applied rotation of the first gear element
2 as a result of the gear ratio.

[0035] A central feature of the different types of the dampers according
to the invention is that the generator is always directly integrated in
the gear itself, independent of the employed gear type. An additional
central feature is that the stator, i.e. the element generating the
exciting magnetic field, which is formed here by the hollow-cylindrical
first gear element 1, is during a movement of the masses always actively
rotated via a pivoting lever and the like, which is for example the case
when a wheel rebounds during installation in an automobile. The
respective gear ratio causes a significantly greater rotation of the
armature, formed by the respective second gear element, which allows
commensurate high current generation efficiency.

[0036] While the magnetic field is in the aforedescribed exemplary
embodiments always generated by stator-side means, whereas the current is
generated on the rotor side, a reverse arrangement of the
current-generating components would also be possible, i.e. the magnetic
field generating means are arranged on the rotor, whereas the current is
induced in windings arranged on the stator side.